A benzothiadiazole thermally excited delayed fluorescent material and a preparation method thereof

Abstract

A benzothiadiazole thermally activated delayed fluorescent material and a preparation method thereof. The present invention relates to a thermally activated delayed fluorescent material, the structure of which is shown in FIG1. ​​The thermally activated delayed fluorescent material is a benzothiadiazole derivative substituted at the 5 and 6 positions. The thermally activated delayed fluorescent material provided by the present invention is suitable for large-scale preparation because of its short synthesis steps, low preparation cost and high product yield. It also has the characteristics of good stability, high quantum yield and easy derivatization. The thermally activated delayed fluorescent material has potential application prospects in electroluminescent devices.

Description

Technical Field

[0001] The invention belongs to the field of organic luminescent materials, and in particular relates to a thermally excited delayed fluorescent material with a benzothiadiazole structure and a synthesis method thereof. Background Art

[0002] Organic light-emitting diodes (OLEDs) have developed rapidly due to their lower manufacturing costs, light weight, high plasticity, better display quality, faster response and other advantages. Significant progress has been made in many related fields. Traditional OLEDs with fluorescent and phosphorescent materials as the light-emitting layer have been limited in further development to a certain extent due to their low efficiency and high cost.

[0003] Professor Adachi of Kyushu University in Japan proposed a new type of organic light-emitting material, namely thermally stimulated delayed fluorescence (TADF) material as the OLED light-emitting layer. This thermally stimulated delayed fluorescence material has a small energy difference between the singlet and triplet states (<0.3eV), which allows for effective intersystem crossing, allowing triplet excitons to be fully utilized, thereby achieving higher luminescence efficiency. Its theoretical internal quantum efficiency (IQE) can reach 100%. Summary of the invention

[0004] The purpose of the present invention is to provide a benzothiadiazole thermally excited delayed fluorescent material, aiming to solve the problems of low efficiency and high manufacturing cost of the light-emitting layer materials used in traditional OLEDs.

[0005] Another object of the present invention is to provide a method for preparing a benzothiadiazole thermally excited delayed fluorescent material.

[0006] A compound with thermally stimulated delayed fluorescence (TADF) property is synthesized by introducing an electron-rich electron donor into a benzothiadiazole electron acceptor, thereby preparing a new organic material with thermally stimulated delayed fluorescence property.

[0007] A benzothiadiazole thermally activated delayed fluorescent material includes seven molecules, and the structural formula is shown below:

[0008]

[0009] The method for preparing the benzothiadiazole thermally activated delayed fluorescent material according to claim 1, characterized in that the preparation method comprises the following steps:

[0010] 1) Prepare the compound of formula IX shown in the following structural formula:

[0011] Wherein R is hydrogen or fluorine;

[0012] The diamine compound of formula VIII and triethylamine are dissolved in CH2Cl2, dichlorothionyl is added dropwise with stirring, and the mixture is refluxed for 4 hours; cooled to room temperature, water is added, and the organic phase is separated; the aqueous phase is extracted twice with CH2Cl2; the organic phases are combined and washed with saturated brine, then dried, concentrated, and purified by column chromatography to prepare the compound of formula IX.

[0013] 2) Prepare the compound of formula I shown in the following structural formula:

[0014]

[0015] The compound of formula IX, phenothiazine, Pd2(dba)3, HP t Bu3BF4 and sodium tert-butoxide are added to toluene and stirred at 50°C for 1 to 5 hours; cooled to room temperature, water is added and the organic phase is separated; the aqueous phase is extracted twice with CH2Cl2; the organic phases are combined and washed with saturated brine, then dried, concentrated, and purified by column chromatography to prepare the compound of formula I.

[0016] 3) Prepare the compound of formula II shown in the following structural formula:

[0017]

[0018] The compound of formula IX, 9,10-dihydro-9,9-dimethylacridine, Pd2(dba)3, HP t Bu3BF4 and sodium tert-butoxide are added to toluene and stirred at 50°C for 1 to 5 hours; cooled to room temperature, water is added and the organic phase is separated; the aqueous phase is extracted twice with CH2Cl2; the organic phases are combined and washed with saturated brine, then dried, concentrated, and purified by column chromatography to prepare the compound of formula II.

[0019] 4) Prepare the compounds of formula III and IV shown in the following structural formula:

[0020]

[0021] The compound of formula IX, phenoxazine, Pd2(dba)3, HP t Bu3BF4 and sodium tert-butoxide are added to toluene and stirred at 50°C for 1 to 5 hours; cooled to room temperature, water is added and the organic phase is separated; the aqueous phase is extracted twice with CH2Cl2; the organic phases are combined and washed with saturated brine, then dried, concentrated, and purified by column chromatography to prepare compounds of formula III and IV.

[0022] 5) preparing a compound of formula V shown in the following structural formula:

[0023]

[0024] Add the compound of formula IV, carbazole and sodium tert-butoxide to DMF and stir at 120°C for 1 to 5 hours; evaporate most of the DMF under reduced pressure, cool to room temperature, add water, and extract three times with CH2Cl2; combine the organic phases and wash with saturated brine, then dry, concentrate, and purify by column chromatography to prepare the compound of formula V.

[0025] 6) Prepare the compound of formula XI shown in the following structural formula:

[0026]

[0027] The diamine compound of formula X and triethylamine are dissolved in CH2Cl2, dichlorothionyl is added dropwise with stirring, and the mixture is refluxed for 4 hours; cooled to room temperature, water is added, and the organic phase is separated; the aqueous phase is extracted twice with CH2Cl2; the organic phases are combined and washed with saturated brine, then dried, concentrated, and purified by column chromatography to prepare the compound of formula XI.

[0028] 7) Prepare the compound of formula VI shown in the following structural formula:

[0029]

[0030] Add the compound of formula XI, carbazole and sodium tert-butoxide to DMF and stir at 120°C for 1 to 5 hours; evaporate most of the DMF under reduced pressure, cool to room temperature, add water, and extract three times with CH2Cl2; combine the organic phases and wash with saturated brine, then dry, concentrate, and purify by column chromatography to prepare the compound of formula VI.

[0031] 8) preparing a compound of formula VII shown in the following structural formula:

[0032]

[0033] Add the compound of formula XI, 3,6-di-tert-butylcarbazole and sodium tert-butoxide to DMF and stir at 120°C for 1 to 5 hours; evaporate most of the DMF under reduced pressure, cool to room temperature, add water, and extract three times with CH2Cl2; combine the organic phases and wash with saturated brine, then dry, concentrate, and purify by column chromatography to prepare the compound of formula VII.

[0034] The theoretical luminous efficiency of an OLED device using a thermally stimulated delayed fluorescent material as a light-emitting layer can reach 100%. The compounds of formulas I to VII provided by the present invention are thermally stimulated delayed fluorescent materials, providing new materials for improving the efficiency of OLEDs. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural diagram of the material of the present invention. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0037] The application principle of the present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0038] Example 1

[0039] 5-(10-phenothiazinyl)[1,2,5]benzothiadiazole(Ⅰ)

[0040]

[0041] The preparation method of the above-mentioned compound of formula I is as follows:

[0042] S101: Preparation of 5-bromo[1,2,5]benzothiadiazole (IX1):

[0043]

[0044] Under argon protection, 4-bromo-o-phenylenediamine (1.0 g, 5.38 mmol) and triethylamine (3.73 mL, 26.88 mmol) were dissolved in CH2Cl2 (20 mL), and dichlorothionyl (1.16 mL, 16.1 mmol) was added dropwise with stirring, and the mixture was refluxed for 4 hours; cooled to room temperature, water was added, and the organic phase was separated; the aqueous phase was extracted twice with CH2Cl2; the organic phases were combined and washed with saturated brine, then dried, concentrated, and separated and purified by column chromatography (PE / EtOAc=15 / 1) to prepare the compound of formula Ⅸ1 (0.99 g, 86%).

[0045] S102: Preparation of 5-(10-phenothiazinyl)[1,2,5]benzothiadiazole (I):

[0046]

[0047] Under argon protection, the compound of formula IX1 (100 mg, 0.47 mmol), phenothiazine (84.5 mg, 0.42 mmol), Pd2(dba)3 (11.7 mg, 0.013 mmol), HP tBu3BF4 (6.1 mg, 0.021 mmol) was added to toluene (5 mL). The mixture was slowly added with stirring at room temperature to a toluene solution (5 mL) of sodium tert-butoxide (44.85 mg, 0.47 mmol). After the addition, the temperature was raised to 110°C and the mixture was reacted for 5 hours. The mixture was cooled to room temperature, and the remaining insoluble catalyst was removed by suction using a sand core funnel, and the mixture was washed twice with dichloromethane. The organic solvent was removed from the filtrate under vacuum conditions, and the mixture was purified and separated by column chromatography (PE / EtOAc=50 / 1) to prepare a red solid compound of formula I (129 mg, 92%).

[0048] Example 2

[0049] 5-(9,9-Dimethylacridinium)[1,2,5]benzothiadiazole(Ⅱ)

[0050]

[0051] The preparation method of the compound of formula II is as follows:

[0052] Under argon protection, the compound of formula IX1 (150 mg, 0.70 mmol), 9,10-dimethyl-9,10-dihydroacridine (97.6 mg, 0.47 mmol), Pd2(dba)3 (42.7 mg, 0.047 mmol), HP t Bu3BF4 (20.0 mg, 0.069 mmol) was added to toluene (5 mL). The mixture was slowly added with stirring at room temperature to a toluene solution (5 mL) of sodium tert-butoxide (67.2 mg, 0.7 mmol). After the addition, the temperature was raised to 110°C and the mixture was reacted for 5 hours. The mixture was cooled to room temperature, and the remaining insoluble catalyst was removed by suction using a sand core funnel, and the mixture was washed twice with dichloromethane. The organic solvent was removed from the filtrate under vacuum conditions, and the mixture was purified and separated by column chromatography (PE / EtOAc=200 / 1) to prepare a red solid compound of formula II (130 mg, 81%).

[0053] Example 3

[0054] 5-(10-phenoxazinyl)[1,2,5]benzothiadiazole(Ⅲ)

[0055]

[0056] The preparation method of the above-mentioned compound of formula III is as follows:

[0057] Under argon protection, the compound of formula IX1 (500 mg, 2.34 mmol), phenoxazine (388 mg, 2.12 mmol), Pd2(dba)3 (80.0 mg, 0.09 mmol), HP tBu3BF4 (30.0 mg, 0.10 mmol) was added to toluene (10 mL). The mixture was slowly added with stirring at room temperature to a toluene solution (10 mL) of sodium tert-butoxide (225 mg, 2.34 mmol). After the addition, the temperature was raised to 110°C and the mixture was reacted for 5 hours. The mixture was cooled to room temperature, and the remaining insoluble catalyst was removed by suction using a sand core funnel, and the mixture was washed twice with dichloromethane. The organic solvent was removed from the filtrate under vacuum conditions, and the mixture was purified and separated by column chromatography (PE / EtOAc=50 / 1) to prepare a red solid compound of formula III (645 mg, 96%).

[0058] Example 4

[0059] 5-Fluoro-6-(10-phenoxazinyl)[1,2,5]benzothiadiazole(Ⅳ)

[0060]

[0061] The preparation method of the above-mentioned compound of formula IV is as follows:

[0062] S401: Preparation of 5-fluoro-6-bromo[1,2,5]benzothiadiazole (IX2):

[0063]

[0064] 4-Bromo-5-fluoro-o-phenylenediamine (2.0 g, 4.9 mmol) and triethylamine (6.8 mL, 24.5 mmol) were dissolved in CH2Cl2 (50 mL), and dichlorothionyl (2.1 mL, 14.7 mmol) was added dropwise with stirring, and the mixture was refluxed for 4 hours; cooled to room temperature, water was added, and the organic phase was separated; the aqueous phase was extracted twice with CH2Cl2; the organic phases were combined and washed with saturated brine, then dried, concentrated, and purified by column chromatography (PE / EtOAc=15 / 1) to prepare the compound of formula IX2 (0.94 g, 80%).

[0065] S202: Preparation of 5-fluoro-6-(10-phenoxazinyl)[1,2,5]benzothiadiazole (IV)

[0066]

[0067] Under argon protection, the compound of formula IX2 (300 mg, 1.29 mmol), phenoxazine (260 mg, 1.42 mmol), Pd2(dba)3 (118 mg, 0.13 mmol), HP tBu3BF4 (37.0 mg, 0.13 mmol) was added to toluene (10 mL). The mixture was slowly added with stirring at room temperature with a toluene solution (10 mL) of sodium tert-butoxide (124 mg, 1.29 mmol). After the addition, the temperature was raised to 110°C and the mixture was reacted for 5 hours. The mixture was cooled to room temperature and filtered with a sand core funnel to remove the remaining insoluble catalyst and the like, and washed twice with dichloromethane. The filtrate was freed from the organic solvent under vacuum and purified and separated by column chromatography (PE / EtOAc=4 / 1) to prepare a red solid compound of formula IV (277 mg, 60%).

[0068] Example 5

[0069] Preparation of 5-(9-carbazolyl)-6-(10-phenoxazinyl)[1,2,5]benzothiadiazole (V)

[0070]

[0071] Under argon protection, carbazole (120 mg, 0.72 mmol) was added to DMF (5 mL), and then potassium tert-butoxide THF solution (1M, 1.01 mL) was slowly added, and the mixture was reacted at 0°C for half an hour. A DMF (5 mL) solution of compound IV (200 mg, 0.60 mmol) was then added under stirring. The mixture was reacted at room temperature for 4 hours. 20 mL of ice water was added and the mixture was filtered with a Bush funnel, and the filtered solid was placed in an oven for drying. The solid was dissolved in an appropriate amount of dichloromethane and separated and purified by column chromatography (PE / EtOAc=4 / 1) to prepare a red solid V (240.8 mg, 84%).

[0072] Example 6

[0073] Preparation of 5,6-di(9-carbazolyl)[1,2,5]benzothiadiazole (VI)

[0074]

[0075] The preparation method of the above-mentioned compound of formula VI is as follows:

[0076] S601: Preparation of 5,6-difluoro[1,2,5]benzothiadiazole (XI):

[0077]

[0078] 4,5-Difluoro-o-phenylenediamine (5.0 g, 34.72 mmol) and triethylamine (24 mL, 0.17 mol) were dissolved in CH2Cl2 (100 mL), and dichlorothionyl (7.5 mL, 0.1 mol) was added dropwise with stirring, and the mixture was refluxed for 4 hours; cooled to room temperature, water was added, and the organic phase was separated; the aqueous phase was extracted twice with CH2Cl2; the organic phases were combined and washed with saturated brine, then dried, concentrated, and purified by column chromatography (PE / EtOAc=15 / 1) to prepare the compound of formula XI (5.0 g, 85%).

[0079] S602: Preparation of 5,6-di(9-carbazolyl)[1,2,5]benzothiadiazole (VI):

[0080]

[0081] Under argon protection, carbazole (640.8 mg, 3.84 mmol) was added to DMF (10 mL), and then potassium tert-butoxide THF solution (1M, 5.23 mL) was slowly added, and the mixture was reacted at 0°C for half an hour. Then, a DMF (10 mL) solution of the compound of formula XI (300 mg, 1.74 mmol) was added under stirring. The mixture was reacted at room temperature for 4 hours. 50 mL of ice water was added and the mixture was filtered with a Bush funnel, and the filtered solid was placed in an oven for drying. The solid was dissolved in an appropriate amount of dichloromethane and separated and purified by column chromatography (PE / EtOAc=50 / 1) to prepare a yellow solid VI (400 mg, 49%).

[0082] Example 7

[0083] Preparation of 5,6-bis(3,6-di-tert-butyl-carbazolyl)[1,2,5]benzothiadiazole (VII)

[0084]

[0085] Under argon protection, 3,6-di-tert-butylcarbazole (356.8 mg, 1.28 mmol) was added to DMF (2 mL), and then potassium tert-butoxide THF solution (1M, 1.45 mL) was slowly added, and the mixture was reacted at 0°C for half an hour. A DMF (6 mL) solution of the compound of formula XI (100 mg, 0.58 mmol) was then added under stirring. The mixture was reacted at room temperature for 4 hours. 20 mL of ice water was added and the mixture was filtered with a Bush funnel, and the filtered solid was placed in an oven for drying. The solid was dissolved in an appropriate amount of dichloromethane and separated and purified by column chromatography (PE / EtOAc=50 / 1) to prepare a yellow solid VII (230 mg, 57%).

Claims

1. A method for preparing a benzothiadiazole thermally activated delayed fluorescent material, characterized in that: The structural formula of the benzothiadiazole thermally activated delayed fluorescent material is as follows: ； The preparation method of the compound III is as follows: Under argon protection, 2.34 mmol of the compound of formula IX1, 2.12 mmol of phenoxazine, 0.09 mmol of Pd2(dba)3, 0.10 mmol of HP t Bu3BF4 was added to 10 mL of toluene; 10 mL of a toluene solution of 2.34 mmol of sodium tert-butoxide was slowly added dropwise to the mixture under stirring at room temperature, and the temperature was raised to 110°C for reaction for 5 hours after the addition was completed; the mixture was cooled to room temperature, and the remaining insoluble catalyst was removed by suction through a sand core funnel, and the mixture was washed twice with dichloromethane; the organic solvent was removed from the filtrate under vacuum conditions, and the mixture was purified and separated by column chromatography to prepare a red solid compound of formula III; The structural formula of the compound IX1 is as follows: ； The preparation method of compound IV is as follows: Under argon protection, 1.29 mmol of the compound of formula Ⅸ2, 1.42 mmol of phenoxazine, 0.13 mmol of Pd2(dba)3, 0.13 mmol of HP t Bu3BF4 was added to 10 mL of toluene; 10 mL of a toluene solution of 1.29 mmol of sodium tert-butoxide was slowly added dropwise to the mixture under stirring at room temperature, and the temperature was raised to 110°C for reaction for 5 hours after the addition was completed; the mixture was cooled to room temperature, and the remaining insoluble catalyst was removed by suction through a sand core funnel, and the mixture was washed twice with dichloromethane; the organic solvent was removed from the filtrate under vacuum conditions, and the mixture was purified and separated by column chromatography to prepare a red solid compound of formula IV; The structural formula of the compound IX2 is as follows: The preparation method of the compound V is as follows: Under argon protection, 0.72 mmol of carbazole was added to 5 mL of DMF, and then 1.01 mL of 1M THF solution of potassium tert-butoxide was slowly added, and the mixture was reacted at 0°C for half an hour, and then 5 mL of DMF solution of 0.60 mmol of the compound of formula IV was added under stirring; the mixture was reacted for 4 hours at room temperature, 20 mL of ice water was added and filtered with a Bush funnel, and the solid obtained by filtration was placed in an oven for drying; the solid was dissolved with an appropriate amount of dichloromethane and separated and purified by column chromatography to prepare a red solid compound V.

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